Method of making insoles



Jan. 23, 1951 s. M. GRISWOLD 2,533,776

METHOD OF MAKING INSOLES Filed Dec. 19, 1946 2 Sheets-Sheet 1 I nyen/for Stan/e l MGfz s wold Jan. 23, 1951 s. M. GRISWOLD 2,538,776

METHOD OF MAKING INSOLES Filed Qec. 19, 1946 2 Sheets-Sheet 2 I n venfor Stanley M Grzlswold By is After/2 Patented Jan. 23, 1951 METHOD OFMAKING INSOLES Stanley M. Griswold, West Newton, Mass., al-

signor to B. B. Chemical 00., Boston, Mass., a corporation ofMassachusetts Application Decen iber 19, 1946, Serial No. 717,121

23 Claims.

This invention relates to methods of making insoles.

Objects of the invention are to provide substantially identical insolesfor welt work and pairs of such insoles each of which is the mirrorimage of the other, and also to provide methods of making welt insoleswith ribs having the strength and rigidity successfully to withstand thestrains incident to the making of a welt shoe as well as those due tosubsequent wear.

Another object is to provide methods of making insoles the ribs of whichare located at precisely predetermined, varying distances from the edgesof the insoles or, differently stated, methods of making insoles in eachof which the feather varies in width at different parts of the insoleaccording to a predetermined plan, the width being usually greatest inthe shank portion, less about the toe, and still less at the ball.

Still another object of the invention is to improve the method of makinginsoles disclosed in United States Letters Patent No. 1,382,818, grantedJune 28, 1921, in the names of D. W. Bunker and C. M. Bradford, whichpatent discloses an insole of the same general type as that of thepresent invention.

This prior insole requires for its formation a mold contoured tocorrespond to the last bottom and having a groove therein correspondingin location to that of the desired rib and a cooperating contouredpatrix by which the canvas is forced into all portions of the groovesimultane-' ously to form the rib and to mold the insole.

The term canvas will be generally used hereinafter to designate thelayer of the insole in which the rib is formed. The fabric usually usedfor reinforcing insoles, known as gem duck, is suitable for the purpose.It is to be understood, however, that other suitable fabrics, whetherwoven or not, may be employed.

The present invention employs a flat grooved matrix in place of the moldand, by progressively tucking the canvas into the groove, dispensesentirely with the use of a corresponding patrix, thus greatly reducingthe cost of the apparatus for making such insoles. Moreover, the matrixbeing flat, each side thereof can readily be provided with a rib-forminggroove, one groove being exactly opposite to the other so that a matingpair of insoles is made with a single solid matrix.

The prior method requires dieing out of the canvas and body portions andtheir careful registration on the molds for the molding operation,whereas by the present method the canvas and body portions may be ofindefinite shape, and, the

matrix being of the shape 01 the last bottom pattern, its edge face isused as a guide in the final trimming operation to produce a pair ofinsoles which exactly fit the bottoms of a pair of lasts when conformedthereto. The method of the prior patent requires sewing of the canvasand body portions together, whereas by the method of the presentinvention the adhesive bond between the canvas and body portion is alonesuflicient to produce a satisfactory insole.

The insole comprises a body layer and an allover layer of stiffenedcanvas in which the rib is formed by a fold of canvas containing a corepiece of suitable material to impart the requisite strength and rigidityto the rib. The core piece preferably has a flange directed inwardly ofthe insole beneath .the canvas to withstand the thrust of the channelguide and the tension of the stitches by which the welt and upper aresecured to the rib. As illustrated, the core piece is of firm material,such as pasteboard or fibrous material impregnated with latex, and mayhave secured to its inner face one part of an L-shaped strip of materialsuch as canvas, the other part forming a flange extending inwardly ofthe insole between the body layer and the canvas, thus forming areinforcement for the rib in the 10- cality where the channel guide runsand where the awl strikes in forming a hole for the needle of the inseamstitching machine.

The canvas used is preferably treated with a stiffening material whichimparts thereto greater firmness and prevents the cement, such as latex,which is later applied to its surface from being absorbed too much bythe canvas. The stiffening material should be such that the canvastreated therewith is limp or can be rendered limp temporarily during theworking of it into the matrix groove and will stiffen after thatoperation. The stiffening material may be thermoplastic so as to berendered limp by application of heat or it may be a stiffening materialthat can be rendered temporarily limp by light application of a solvent.In any case, the stiffening material should be water-resistant. Examplesof such materials will be given later.

In making such insoles, a matrix is employed which is preferably made bypractice of the method disclosed and claimed in a copending applicationfor Letters Patent of the United States Serial No. 717,122, filedDecember 19, 1946, in the names of Stanley M. Griswold and Hans C.Paulsen.

This matrix consists of a block of suitable material having the shape ofthe desired insole and having opposite parallel faces in each of whichis formed a groove as wide as the thickness of the desired rib and or adepth correspondlng to the height of rib desired, each groove beinglocated with respect to the edge or the blow; substantially as the ribis to be located with respect to the edge of the insole. 1n the edgerace or'the matrix is a groove ending at the breast line for use inlocating the matrix for subsequent operations thereon, the bottom ofsaid groove being at a uniform predetermined distance from the ribgrooves. For convenience in trimming the insole, the matrix ispreferably made somewhat smaller than the desired insole, for exampleone thirty-second of an inch. The matrix may be provided at its heelportion on each side with a tang to hold one end of the piece of canvasand with a pairof pins to prevent the heel portion of the insole fromslnftlng on the matrix during a subsequent trimming operation.

The invention comprises a method of making insoles which may beimplemented by the abovereferred-to matrix. A piece of canvas,preferably prepared as above described, is lard cement side out upon thematrix, the tang at the heel end being used to hold one end of thecanvas while pulling it straight. The matrix may be located for thefollowing operation by a stop engaging the rear end of the groove in itsedge face. and then beginning at the breast line on one side of thematrix the canvas is progressively tucked by a suitable tool into thegroove on the upper side of the matrix, thus forming a fold in thecanvas, the matrix being guided for the operation of the tool by a guideengaging the bottom of the groove in the edge face of the matrix. Intothis fold, immediately after its formation, a core piece may beinserted, the formation of the fold and the insertion of the core piecebeing continued progressively about the matrix until the other end ofthe breast line is reached. The tucking and core-piece-insertingoperations are facilitated by rendering the stiffened canvas limp duringthe operation thereon. Where a solvent-soften-able stiffening materialis used, a solvent for the stiffening material is applied to render itlimp, the solvent evaporating after the tucking and core-piece-insertingand restoring the canvas to a stiffened condition. When a thermoplasticstiffening material is used, it is convenient to render the canvas limpby heating it. This may be done by directing a blast of hot air upon thecanvas in the region where the tucking and core-piece-insertingoperations are taking place. The canvas is quickly restored to itsstiffened condition as it cools.

After performing the above-described operations on one side of thematrix, it is turned the other side up and the operations repeated onthat side of the marix.

A body layer which has been coated on one side with cement, such asnatural or synthetic latex, is applied to each side of the matrix withits cement side in contact with the cemented canvas thereon and theassembly subjected to pressure to cause the body layer on each side ofthe matrix to become firmly bonded to the canvas layer. The parts of thebody layer and canvas which extend beyond the edge face of the matrixare now trimmed away one thirty-second of an inch outwardly beyond theedge face of the matrix, allowance for this having been made in makingthe matrix. The pair of completed, accurately mated and accurately sizedinsoles are then removed from the matrix. When a body layer of flexiblematerial such as split leather ls employed, insoles which readilyconform to the last bottom without molding are pro- QULEQ, and by thismethod there is no restriction as to the character of the body layerwhich may be as thin and flexible as is desired. Thus the flexibility ofthe insole is under control of the manufacturer, the requisite strengthin the insole being provided for largely by the stiffened canvas.

These and other features of the invention will appear more full from thefollowing description when read in connection with the accompanyingdrawings and will be pointed out in the appended claims.

In the drawings,

Fig. 1 is a plan view of the-matrix;

Figs. 2, 3 and 4 are respectively sections of the matrix taken on theline lI-II, III--III and IV-IV of Fig. 1;

Fig. 5 is a plan view showing the. matrix with a piece of convas appliedthereto and held by the tang at its rear end; r

Fig, 6 is a view, partly in section, showing the operation ofprogressively tucking the canvas into the groove and inserting a corepiece into the fold of the canvas;

Fig. 7 is a perspective view of the form of the core piece illustratedin Fig. 6;

Fig. 8 is a fragmentary, transverse section of the matrix after theoperation illustrated in Fig; 6 has been performed;

Fig. 9 is a perspective view of a core ing an integral flange;

Fig. 10 is a perspective view of a core piece similar to Fig. 7 in whichpart of an L-shaped strip of canvas has beencemented to the core piece,the remainder of the canvas forming a flange thereon;

Fig. 11 is a fragmentary sectional view of the matrix after the corepiece illustrated in Fig. 10 has been introduced into the fold of canvasby the operation illustrated in Fig. 6;

Fig. 12 is a perspective view of the matrix after the canvas and thecore piece of Fig. 10 have been progressively formed into the groove bythe method illustrated in Fig. 6;

Fig. 13 is a transverse section of the matrix on the line XIII-XIII ofFig. 12;

Fig. 14 is a sectional view similar to Fig. 13 showing the matrix ofFig. 12 after the body layers have been applied to each side of thematrix and pressure applied thereto between platens of a press;

Fig. 15 is a fragmentary sectional view of the matrix and the twoinsoles after the portions of the body layers and canvas projectingbeyond the matrix have been trimmed;

Fig. 16 is a plan view of the completed insole; and

Fig. 17 is a sectional detail on the line XVII XVII of Fig. 16.

' The matrix, as shown in Figs. 1 to 4, consists of an insole-shapedblock 20 of suitable material having parallel, fiat faces in each ofwhich is formed a groove 22 corresponding in depth, width and locationto the height, thickness and location of the ribs to be formed on a pairof insoles. When the material used for the block is not of a verydurable nature, for example hard wood, each face of the block, beforegrooving, is reinforced by cementing to each face a thin plate 24 ofmetal such as aluminum alloy. Near the heel end of the matrix on eachside is a tang 26 on piece havwhich the end portion of a piece of canvasor duck may be impaled. Pins 28 are also provided at the heel end of thematrix on each side to prevent lateral shifting of the heel portion ofthe insole with respect to the matrix during trimming. The trimming ispreferably done about of an inch from the matrix and therefore thematrix is made of an inch smaller all around than the size of the insoledesired. A groove 30, the bottom of which is at a predetermined uniformdistance from the grooves 22, is formed in the edge face of the matrix,the rear end of this groove being utilized in locating the matrix forsubsequent operations.

The canvas may be treated with various waterresistant stiffeningmaterials which can be destifiened to facilitate the tucking operation.The stiffening materials may be thermoplastics such as rosin, rosinderivatives and coumarone-indene resin V, which may be that manufacturedby The Barrett Company, 40 Rector Street, New York, N. Y., the requisitebeing that the canvas may be rendered temporarily limp by application ofheat hereto to facilitate forming it into the groove of the matrix and,upon cooling, will reassume its strength and stiffness.

The stiffening material may be one that can be rendered limp byapplication of a solvent thereto just before the canvas is applied tothe matrix, evaporation of the solvent after the tucking operationrestoring the canvas to its stiffened condition. Examples of materialthat may be so used are zein, which may be dissolved in an alcohol-watersolution, for example 83% alcohol,

17% water, pyroxylin dissolved in acetone, or cel- 1 lulose acetatedissolved in acetone, methylethylketone, alcohol or xylol. Thestiffening solution is applied to the canvas and allowed to dry and,just before the piece of canvas is applied to the matrix, it receives alight application of the appropriate solvent which renders it limp toassist the tucking operation and soon evaporates to render the canvasstiff again.

A piece of canvas 32 (Fig. 5), which has been treated with a stiffeningsolution (for example, a 15% solution of the above-mentioned resin innaphtha) and allowed to dry and then coated with natural or syntheticlatex and allowed to dry, is laid on the matrix cement side up andpressed down on the tang 26. The canvas is then pulled straight andprogressively tucked by a tool 34 (Fig. 6) into the groove 22, startingat the breast line on one side and extending along the shank andforepart to the other end of the breast line. concomitantly with thetucking of the canvas 32 into the groove 22, a core piece 36 (Fig. 7)may be tucked into the fold made in the canvas by tucking it into thegroove and is hammered down by a hammer 38 flush with the canvascovering the matrix. The cross-section of the matrix after thisoperation is shown in Fig. 8,

In order to facilitate the tucking of the canvas into the groove, ablast of hot air is blown through a tube 39 (Fig. 6) upon that portionof the canvas where the tucking operation is occurring. The hot air, byheating the stiffening material and the cement on the canvas. renders ittemporarily limp and tractable so that it can readily be tucked into thegroove. The softened materials as they cool assist in holding the corepiece 36 firmly in place. To supply the blast of hot air, apparatussimilar to that disclosed in United States Letters Patent No. 1,777,744,granted October '7, 1930, and No. 1,869,737, granted August 2, 1932, inthe name of A. A. Breuer, may be employed.

While the canvas-tucking and, core-piece inserting operations may beperformed by hand, I prefer to employ a machine of the type disclosedand claimed in United States Letters Patent No. 2,493,207, grantedJanuary 3, 1950, and No. 2,494,578, granted January 17, 1950, in thename of Hans C. Paulsen, by which the location of the matrix by thegroove 30, the tucking of the canvas into the groove 22, and theinsertion of the core piece 39 into the fold of the canvas are performedsubstantially simultaneously, that is, concomitantly.

Preferably a core piece having a reinforcing flange is employed. Theflange may be integral with the core piece, as shown in Fig. 9, or itmay be formed by a wider strip of canvas 40, one half of which iscemented to the core piece 36 and the other half bent at right angles toform a flange 42. A section of the matrix, after the abovedescribedoperations have been performed using the flanged core piece of Fig. 10,is shown in Fig. 11.

The operations of applying canvas and tucking it into the groove arethen repeated upon the opposite side of the matrix, the assembly thenappearing as shown in Figs. 12 and 13. Insole body blanks 44, which havebeen prepared by coating one side thereof with natural or syntheticlatex cement and allowed to dry, are placed one on each side of thematrix, their cemented faces in contact with the canvas on the matrix.This assembly is then subjected to heavy pressure, for example betweenplatens 46, 48 of a press such as a hydraulic press, thus causing thebody portions 44 to be firmly bonded to the canvas layers 32. A sectionof the matrix during the pressing operation is shown in Fig. 14.

The portions of the canvas 32 and of the body blanks 44 which extendbeyond the edge face of the matrix are now trimmed away, the cuts beingmade about a; of an inch from the edge face of the matrix as shown inFig. 15. The trimming operation may advantageously be performed by useof the machine disclosed and claimed in United States Letters Patent No.2,472,228, granted June '7, 1949, or by the machine disclosed andclaimed in an application for United States Letters Patent Serial No.30,005, filed May 29, 1948, both in the name of Hans C. Paulsen. Thepair of completed mating insoles is now removed from the matrix, whichmay be used indefinite'y to produce pairs of insoles, the right insolesbeing identical and one of each pair being the exact mirror image of theother.

One of the completed insoles is shown in Fig. 16, the other being, ofcourse, exact'ly similar except that it is for the other foot. A sectionof a portion of the completed insole is shown in Fig. 17.

The insole herein disclosed but not claimed is being disclosed andclaimed in an application for Letters Patent of the United States SerialNo. 30,799, filed June 3, 1948, in my name.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent of the United States is:

1. That improvement in methods of making welt insoles which comprisesproviding an insoleshaped matrix having a rib-forming groove therein,applying a layer of fabric over the matrix, and progressively tuckingthe fabric into the groove in the matrix.

2. That improvement in methods of making welt insoles which comprisesproviding a matrix having the shape and substantially the size of theinsole desired and having therein a groove corresponding to the desiredlocation of an insole rib, laying a sheet of canvas over the groovedface of the matrix, progressively tucking the canvas into the groove,cement-attaching a body blank to the canvas, and trimming the canvas andbody blank to the shape of the matrix.

3. That improvement in methods of making welt insoles which comprisesproviding an insoleshaped matrix having a rib-forming groove therein,applying a layer of canvas over the matrix, progressively tucking thecanvas into a groove to form a fold thereinand concomitantly inserting acore piece into the fold of canvas.

4. That improvement in methods of making welt insoles which comprisesproviding an insoleshaped matrix having a rib-forming groove therein,applying" a layer of canvas over the matrix, progressively tucking thecanvas into the groove, progressively inserting a core piece into thefold of the canvas, and cementing a body blank into the canvas while therib is in the groove.

5. That improvement in methods of making welt insoles which comprisesproviding an insoleshaped matrix having a rib-forming groove therein,providing a layer of canvas impregnated with thermoplastic stifieningmaterial, laying the stifiened canvas over the matrix, heating thecanvas to make it limp,-and progressively tucking the canvas into thegroove of the matrix.

6. That improvement in methods of making welt insoles which comprisesproviding an insoleshaped matrix having a rib-forming groove therein,providing a layer of canvas stiffened with thermoplastic resinousmaterial, applying the stiffened canvas to the matrix, blowing hot airon the canvas locally to render it limp, progressively tucking the limpcanvas into the groove of the matrix, and simultaneously andprogressively inserting a core piece into the fold of the canvas.

7. That improvement in methods of making welt insoles which comprisesproviding an insoleshaped matrix having a rib-forming groove therein,applying over the groove in the matrix a layer of canvas stiffened whichconsists in stiffening the canvas with thermoplastic material, blowinghot air upon the canvas to render it limp, and progressively tucking thelimp canvas into the groove.

8. That improvement in methods of making the canvas to render ittemporarily limp, progressively tucking the canvas into a groove to formthe rib, and securing a body portion to the canvas.

11. That improvement in methods of making welt insoles which comprisesstiflening canvas with thermoplastic stiflening material, providing aninsole-shaped matrix having a rib-forming groove therein, applying thestiflened canvas to the matrix, heating the canvas to render it limp,and progressively tucking the canvas into groove to form a rib thereon.

12. That improvement in methods of making welt insoles which comprisesproviding a matrix of the size and shape of an insole having therein agroove corresponding to the desired location of an insole rib, laying apiece of canvas impregnated with thermoplastic material over the matrix,blowing hot air locally on the canvas to render it limp, progressivelyforcing the limp canvas into the groove, cementing an insole body blankto the canvas, trimming the canvas and body blank to the shape of thematrix, and removing the insole from the matrix.

13. That improvement in methods of making welt insoles which comprisesproviding an insoleshaped matrix having a rib-forming groove therein,applying a layer of fabric over the matrix, progressively tucking thecanvas into a groove, progressively inserting a core piece having aninwardly directed flange into the fold of the canvas, and cementing abody blank to the canvas while the rib is in the groove.

14. That improvement in methods of making welt insoles which comprisesproviding a matrix of the size and shape of an insole having therein agroove corresponding to the desired location of an inso'le rib, laying apiece of canvas over the matrix and progressively forcing the canvasinto welt insoles which comprises providing an insoleshaped matrixhaving a rib-forming groove therein, providing a layer of canvas largerthan the matrix stiifened which consists in stiffening the canvas withthermoplastic material, blowing hot air on the canvas to render it limp,progressively tucking the canvas into a groove, and. progressively andsimultaneously inserting a core piece into the fold in the canvas.

9. That improvement in methods of making welt insoles which comprisesproviding an insoleshaped matrix having a rib-forming groove therein,providing a layer of canvas larger than the matrix, stiffening thecanvas with waterresistant material, rendering the canvas temporarilylimp, progressively tucking the canvas into a groove to form a rib, andsecuring a body portion to the canvas.

10. That improvement in methods of making welt insoles which comprisesproviding an insoleshaped matrix having a rib-forming groove therein,providing a layer of canvas to cover the matrix, applying a solution ofstiffening material to the canvas, letting it dry, then treating thegroove, cementing an insole body blank to the canvas, trimming thecanvas and body blank to the shape of the matrix, and removing theinsole from the matrix.

15. That improvement in methods of making welt insoles which comprisesproviding a matrix having the shape and substantially the size of theinsole desired and having in one face a groove corresponding in depth,width and location to the height, thickness and location of the desiredrib, forming a piece of canvas into the groove, forcing a core pieceinto the fold of canvas thus formed, applying to the canvas an insolebody blank, and trimming the canvas and body blank to the shape of thematrix.

16.- That improvement in methods of making welt insoles which comprisesproviding a matrix having the shape and substantially the size of theinsole desired and having in one face a groove corresponding in depth,width and location to the height, thickness and location of the desiredrib, forming a piece of canvas into the groove, forcing a core piecehaving a flange thereon directed inwardly of the insole into the fold ofcanvas thus formed, applying to the canvas an insole body blank, andtrimming the canvas and body blank to the shape of the matrix.

17. That improvement in methods of making welt insoles which comprisesproviding a matrix having a flat face of the shape and substantially thesize of the insole desired and having in said face a groovecorresponding in depth, thickness and location to the height, thicknessand location of the desired rib, progressively forming a piece of canvasinto the groove of the matrix and substantially simultaneouslyprogressively introducaoasma I ing a core piece into the'fold of canvasthus formed, applying to the canvas on the matrix a cemented insole bodyblank, applying pressure to cause adhesion between the body blank andthe canvas, and trimming the canvas and body blank to the shape of thematrix.

18. That improvement in methods of making welt insoles which comprisesproviding a matrix having flat parallel faces of the shape andsubsta'ntially the size of the insole desired and having in each fiatface a groove corresponding in depth, thickness and location to theheight, thickness and location of the desired rib, progressively forminga piece of canvas into the groove on one face of the matrixand-substantially simultaneously progressively introducing a core pieceinto the fold of canvas thus formed, repeating the operation on theother flat face of the matrix, applying to each face of the matrix aninsole body blank, applying pressure to cause adhesion between the bodyblanks and the canvas, and trimming the canvas and body blank to theshape of the matrix.

19. That improvement in methods of making welt insoles which comprisesproviding a matrix of the shape of an insole, said matrix having in eachface a groove corresponding in location to the desired location of theinsole rib, laying a piece of canvas on one side of the matrix,progressively tucking the canvas into the groove, reversing the matrix,applying another piece of canvas to the other side of the matrix,progressively forming the canvas into the groove, cementing an insolebody blank to the canvas on each side of the matrix, trimming the canvasand said body blank on each side of the matrix to the shape of thematrix, and removing therefrom the two completed insoles.

welt insoles which comprises providing amatrix having the shape andsubstantially the size of the insole desired and having therein a groovecorresponding to the desired location of an insole rib, laying a sheetof canvas containing softenable stifiening material over the groovedface of the matrix, softening the stiffening material, progressivelytucking the softened canvas into the groove throughout the extent of thegroove, cement-attaching a body blank to the canvas, and trimming awayportions of the canvas and body blank extending beyond the edge of thematrix.

21. That improvement in methods of making welt insoles which comprisesproviding a matrix having the shape and substantially the size of theinsole desired and having therein a groove corresponding to the desiredlocation of an insole 20. That improvement in methods of making.

rib, laying a sheet of canvas carrying thermoplastic stiffening materialover the grooved face of the matrix, progressively heating the canvas atthe working point to render it limp, progressively tucking the limpcanvas into the groove throughout its extent, cement-attaching a bodyblank to the' canvas, and trimming the body blank and canvas to theshape of the matrix.

22. That improvement in methods of making welt insoles which comprisesproviding a matrix having theshape and substantially the size of theinsole desired and having therein a groove corresponding to the desiredlocation of an insole rib, laying a sheet of canvas over the groovedface of the matrix, progressively tucking the canvas into the groove,progressively inserting a core piece into the fold formed by the tuckingoperation concomitantly therewith, cementattaching a body blank to thecanvas, and trimming away portions of the body blank and canvasextending beyond the matrix.

23. That improvement in methods of making welt insoles which comprisesproviding a matrix having the shape and substantially the size of theinsole desired and having therein a groove corresponding to the desiredlocation of an insole rib, laying a sheet of canvas stiffened withthermoplastic resinous material over the grooved face of the matrix,blowing hot air on the canvas locally to render it limp, progressivelytucking the limp canvas into the groove to form a fold therein andsimultaneously and progressively inserting a core piece into the fold ofthe canvas, cementing a body blank to the canvas, and

trimming the body blank and canvas to the shape of the matrix.

STANLEY M. GRISWOLD.

,2 REFERENCES CITED 40 The following references are of record in thefile of this patent:

UNITED STATES PATENTS Number Name Date 1,018,132 Preble Feb. 20, 19121,022,391 Preble Apr. 2, 1912 1,175,200 Thompson Mar. 14, 1916 1,382,818Bunker et al. June 28, 1921 2,068,706 Ray Jan. 26, 1937 5 2,142,332Ridderstrom Jan. 3, 1939 2,348,327 Calleo May 9,1944 2,361,941 HarrisonNov. 7, 1944 FOREIGN PATENTS Number Country Date 211,776 Germany July15, 1909 315,522 Germany Nov. 7, 1919 Certificate of Correction PatentNo. 2,538,776 1 STANLEY M. GRISWOLD It is hereby certified that errorappears in the printed specification of the above numbered patentrequiring correction as follows Column 7, lines 46 and 47, and lines 55and 56, strike out the words which consists in stiflening the canvas;

and that the said Letters Patent should be read as corrected above, sothat the same may conform to the record of the case in the PatentOlfice.

Signed and sealed this 29th day 0t May, A. D. 1951.

' THOMAS F. MURPHY,

Assis iant Commz'ssz'oner of Patents.

January 23, 1951

